This is a comprehensive research proposal designed to improve the treatment of childhood cancer by conducting clinical investigations as a member of Children's Cancer Study Group (CCSG), and by independently conducting other research which is directly related to the mission of CCSG. This proposal is divided into five general categories: 1. Conducting Phase I, II and III clinical investigations as a member of CCSG. 2. Exploring the therapeutic usefulness of new agents, new modalities and new ways of using established agents both in group-wide studies and as an independent institution performing pilot studies for CCSG. 3. Perform pharmacological and immunological studies to provide background information for CCSG studies in progress and for future study development. 4. Study the natural history of selected childhood cancers to define the variables required for performance of statistically valid clinical investigations. 5. To provide appropriate medical and emotional supportive care to study patients to enhance the probability of success of the clinical investigations undertaken. Bibliographic references: Higgins, G.R., Parker, C.E., Faust, J.A., and Rosenfeld, M.: "Hepatitis-Associated (Australia) Antigen and Down's Syndrome". Amer, J. Mental Deficiency, Vol. 78, No. 4, pp. 426- 428, 1974; Barak, Yigal, Shore, Nomie A., Higgins, Gussie R., and Vadakan, Vibul, V.: "Functional cellular maturation in cultures of human hematopoietic cells." British J. of Haematology, 1974, 27, p. 543.